Wire-cut electrical discharge machine with electric shock preventer

Abstract

A wire-cut electrical discharge machine having a device for preventing an accident due to an electrical shock, wherein a guide roller (34a) disposed just before a collection box (38) for collecting a used electrode wire (30) passed through an electrospark machining area (36) is attached to a base plate (56) made of a conductive material, the base plate being fixed to a machine body (26) through an insulating plate (58), and a current leaking to the base plate caused by a disturbance of the running of the electrode wire is led to a safety circuit (50) through a lead wire (52), and a current leakage signal is output whereby an electric power supply of a electric power source (51) is rapidly stopped to prevent an accident due to an electric shock.

We claim: 
     
       1. A wire-cut electrical discharge machine having a means for preventing an accident due to an electric shock, wherein said machine guides an electrode wire which is fed from an electrode wire supply reel, and to which an electric power is supplied from an electric power source via an electric power supply member, and runs to an electrode wire collection section through an electrospark machining area in which a workpiece is machined by an electrospark between the workpiece and the electrode wire, to the electrode wire collection section by means of a roller device disposed just before the electrode wire collection section, said means comprising: a safety circuit for stopping an electric power supply from said electric power source by a current signal;   a conductive base plate made of a conductive material supporting said roller device;   an insulating layer disposed between and electrically insulating said conductive base plate and a machine body of said wire-cut electrical discharge machine to which said conductive base plate is attached; and   a lead wire for leading a current leaking from said electrode wire to said conductive base plate, to said safety circuit.   
     
     
       2. A wire-cut electrical discharge machine having a means for preventing an accident due to an electric shock according to claim 1, wherein said roller device is covered with a box type openable cover made of an insulating material. 
     
     
       3. A wire-cut electrical discharge machine having a means for preventing an accident due to an electric shock according to claim 2, wherein said lead wire is led backward toward a rear side of said machine body located behind said conductive base plate so that interference is prevented when said box type cover is opened or closed.